I don't think all prefabs are awful... (though many of them are.)I refrain from commenting on prefab coops post usually;; because some of the pros here want toView attachment 2933460 for my views...
Yes I am aware that most of the prefab coops are too small, and not QUALITY MADE.
Yes, I am aware that they state the capacity unrealistically.
BUT I DO NOT DISCOURAGE PEOPLE FROM BUYING THEM. We all need to start somewhere,, Some peeps get chickens,, and after short time,, decide chickens are NOT FOR THEM.
Then they are not too much $$$$in the hole.
Then it comes to a point like where you are at. You want to keep chickens,, and decide to modify, and enlarge. Nothing wrong here.
I started off with a prefab as well precisely because I didn't want to sink a lot of money in and then decide chickens weren't for me (the run we spent money on, mainly because it could be turned into a dog kennel or a fenced-in garden). After 2 years I upgraded to a more proper coop, to expand the flock and to save my aching back!
My old prefab wasn't wasted at all. I dismantled it and the majority of it found new purpose... I got a brooder/isolation cage out of it, a covered feed station, a compost sifter. Just for the brooder section alone it was worth it, I couldn't have built anything more suitable myself. And it's held up well despite sitting out in the weather for 5 years.
x2. The only way to know for sure if there's a draft is to run a test inside the coop. Even if someone has the same coop as you and makes the same modifications, their weather/wind patterns won't be the same as yours, so one coop could be draft free while the other is very drafty simply based on the location the coop sits.
Example: I have my top roost bar sitting between 2 open windows 99% of the year, as very rarely does the wind direction blow into either of those windows.
